The extremely power saving RF transmitter module STM 330 of EnOcean is optimized for realization of wireless and maintenance free temperature sensors, or room operating panels including set point dial and occupancy button with a minimum number of external components. The module provides an integrated calibrated temperature sensor.  

Power supply is provided by a small solar cell, an external energy harvester, or an external 3 V battery. An energy storage is installed to bridge periods with no supply from the energy harvester. The module provides a user configurable cyclic wake up. After wake up the internal microcontroller reads the status of the temperature sensor and optional set point dial. A radio telegram will be transmitted in case of a significant change of measured temperature or set point values or if the external occupancy button is pressed. In case of no relevant input change a redundant retransmission signal is sent after a user configurable number of wake-ups to announce all current values. In addition to the cyclic wake-up, a wake up can be triggered externally using the input for the occupancy button or the internal LRN button.